Process for bleaching old papers, paper-stock, straw, &amp;c.



No Drawing.

7 JOHN H. MELCHERS, OF DECATUR, ILLINOIS.

PROQESS FOR BLEACHING OLD PAPERS, PAPER-STOCK, STRAW, 8w.

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To all whom it may concern Be it known that I, JOHN H. MnLoHERs, a citizen of the United States, and a resident of Decatur, in the county of Macon and State of Illinois, have invented a new and, Improved Process for Bleaching Old- Papers, Paper-Stock, Straw, &c., of which the following is a full, clear, and exact description.

My invention relates to a process for bleaching old papers, paper stock, straw, etc., and it consists in the'various steps hereinafter set forth. I

An object of my invention is to provide a process by means of which the coloring matter, ink, etc., may be removed from old papers so as to make stock of pristine whiteness.

A further object of my .invention is to provide a process for bleaching paper stock in which there are iron salts.

A further object of my invention is to provide a process which is comparatively simple and inexpensive for carrying out the first-mentioned objects.

-In the bleachingof old papers which contain ink, anilin, colors etc., the difliculty has heretofore been ingetting rid of the iron salts which exist, or which are formed by precipitation. These salts tend to give the pulp a yellowish tint even when the main. substance of the coloring matter is .destroyed. The manner in 'whichIovercome this difliculty is best explained by outlining the operations necessary for carrying out my process.

Specification of Letters Patent;

Patented July 9, 1912 Application filed August 17, 1911. Serial No. 644,582.

The material to be bleached is first beaten into a pulp with water. A quantity of alka- 1 line sulfid is then added. This may consist of calcium sulfid (Gas) or potassium sulfid (K S). The addition of the calcium sulfid decomposes the coloring matter. The pulp is then washed in the customary way and neutralizedjwith oxalic acid C I LU and is the solution with oxalic acid and subsequently treating with hyposulfurous acid.

2. The herein described process of bleach ing old papers, paper stock, straw, etc., which consists in pulping the material, treating it with calcium sulfid, neutralizing the solution with oxalic acid and-treating theneutralized solution with hyposulfurous acid.

JOHN H. MELOHERS.

Witnesses i L. C. WHEAT, JACOB H. LATHAM. 

